Typically, pressure vessels capable of containing liquids or gases at significant pressures have involved fixed shape cylinders or spheres formed of high-strength metals such as steel or aluminum. Such pressure vessels, while successful for their designed applications, involve a number of problems. First, such metallic cylinders are relatively heavy compared to the gases or fluids that they contain. Second, pressure cylinders contain all of the gas or liquid in a single space. Should the vessel rupture, the entire vessel is destroyed, often with a violent explosion sending shards of metal in all directions. Third, metallic cylinders have a definite shape and cannot be adapted to fit readily in many space-constrained applications. The present invention involves a number of small cells linked to each other by small conduits. The cells are collected in a flexible manifold that allows the collection of cells to be arranged in a variety of different configurations. A pressure vessel of this type can be lightweight, adaptable to a variety of spaces and unusual applications, and is inherently safer in rupture situations.
The present invention is easily adapted to a number of valuable applications through the use of modem, high-strength materials and manufacturing techniques. The pressure handling capability of the vessel can be enhanced through the use of braiding, hoop-winding and overlayment with flexible, high-strength fabric and braiding materials. The pressure vessel may then be further strengthened through the use of plastic resin coatings or the addition of external reinforcement rings. The purity of liquids or gases contained in the vessel may be controlled through the use of special lining tubes placed within the vessel cells during construction. The vessel cells may be prevented from collapsing as gasses or liquids are removed by the introduction of special sponges to the cells during fabrication. For certain special applications, the pressure vessel cells may be fitted with removable, resealable ports, permitting the introduction of relatively large matter into the cells.
A particular problem associated with pressure vessels operated at high pressure is the conditions under which they may fail. Metallic cylinders are particularly dangerous in this regard as they may fragment suddenly if aged or fatigued from many use cycles, even if equipped with overpressure release devices. The present invention provides for a number of controlled pressure release mechanisms that are easily incorporated into the flexible pressure vessels.
The use of numerous small linked pressure vessels also present problems related to effectively joining such vessels together. The present invention provides for novel manufacturing methods for joining such cells.
Various designs have been developed using linked cell technologies. U.S. Pat. No. 6,047,860 issued to Sanders, the present inventor, is directed to a container system for pressurized fluids. The system includes a plurality of ellipsoidal chambers connected by a tubular core. The apertures into each of the chambers are of comparatively small size so that the rate of evacuation may be controlled if a single chamber is ruptured. Thus, the vessels are resistant to explosive rupturing. The container system comprises a plurality of chambers and a tubular core. The size of the apertures in the core are pre-selected so as to control the rate of evacuation of pressurized fluid from chambers. Each of the chambers is generally ellipsoidal and molded of a synthetic material with open front and rear ends. The tubular core is sonically welded to the chamber shells and the exterior of the shells are wrapped with pressure resistant reinforcing filaments. A protective plastic coating is applied to the exterior of the filament wrapped shells.
U.S. Pat. No. 2,222,762 issued to Bebor et al., discloses hollow metal bodies and means for producing them. The hollow bodies described in this invention are particularly adapted for use as pressure vessels and may be produced from tubular bodies by expanding the walls. The zones may comprise spaced spheroids joined together by parts of the initial tube. The hollow bodies described are made by placing a cylindrical tube into a suitable mold and then heating until the metal possesses the plasticity for expanding. By exerting an axially directed compressive force against the ends of the tube and simultaneously applying a high fluid pressure within the tube, the tube ball is axially compressed or upset while portions of the wall are expanded against the walls of the mold surrounding the tube. By suitably adjusting the axial thrust and expanding pressures, the hollow body is formed to possess the same wall thickness and resistivity to pressure yet have the form of a plurality of spaced spheroids adjoined together by parts of the initial tube.
U.S. Pat. No. 4,946,056, issued to Stannard, is directed to a fabricated pressure vessel that is used for the containment of pressurized fluids. The multi-lobed tank comprises a series of cylindrical lobes connected side by side and separated by a septa. Openings or ports in the septa enable fluid communication between the lobes.
U.S. Pat. No. 2,823,668 issued to Van Court et al. describes an inflatable splint. The wrapper of the splint comprises a double layer of material defining a series of flexible fluid chambers divided into elongated enclosures by cementing or heat sealing. It should be noted that the chamber walls are left open at their upper and lower ends whereby all of the elongated fluid chambers are in fluid communication with one another.
U.S. Pat. No. 5,704,512 issued to Falk et al., discloses a vessel that is used for a pressure vessel and made of plastic. The vessel includes a centered tubular part interconnected to a plurality of interconnected fluid compartments distributed peripherally in an annular fashion and thus enclosing the central compartment. The vessels described in this invention may be used to hold liquefied petroleum gas, compressed air, as well as various fire-fighting materials.
While other variations exist, the above-described designs involving linked cell technologies are typical of those encountered in the prior art. It is an objective of the present invention to provide a flexible pressure vessel that is capable of maintaining gasses or liquids at relatively high pressures. It is a further objective to provide this capability in a vessel that is light in weight and that presents a significantly reduced risk of injury in rupture situations. It is a still further objective of the invention to provide a pressure vessel that may be easily adapted to a variety of space constraints. It is yet a further objective to provide a pressure vessel that is durable, easily serviced, and that may be produced inexpensively. It is still a further objective of the invention to provide means for easily increasing the pressure handling capability of the vessel through the addition of external overwrapping, banding or overlayment with high-strength materials.
It is another objective to provide means for controlling the purity of liquids or gasses introduced into the vessel. Further, it is an objective to provide means for introducing solid material into the pressure cells of the vessel through resealable ports in the vessel pressure cells. It is also an objective of this invention to provide for flexible pressure vessels that provide for a controlled release of pressure in overpressure situations. Finally, it is an objective of the invention to provide for safe, efficient and effective means for joining multiple flexible pressure vessels together.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.